I. Field
The present invention relates generally to communication, and more specifically to power control for a wireless communication system.
II. Background
A wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations.
Multiple terminals may simultaneously transmit on the reverse link by multiplexing their transmissions to be orthogonal to one another. The multiplexing attempts to achieve orthogonality among the multiple reverse link transmissions in time, frequency, and/or code domain. Complete orthogonality, if achieved, results in the transmission from each terminal not interfering with the transmissions from other terminals at a receiving base station. However, complete orthogonality among the transmissions from different terminals is often not realized due to channel conditions, receiver imperfections, and so on. The loss in orthogonality results in each terminal causing some amounts of interference to other terminals communicating with the same base station. Furthermore, the transmissions from terminals communicating with different base stations are typically not orthogonal to one another. Thus, each terminal may also cause interference to terminals communicating with nearby base stations. The performance of each terminal is then degraded by the interference from all other terminals in the system.
There is therefore a need in the art for techniques to mitigate the effects of interference so that improved performance may be achieved.